Objective       To determine the effect of Runx3 in drug resistance against hepatocellular carcinoma cells.       Methods       HepG2/cisplatin(CDDP) kinetic anti-cancer drug resistance model was constructed using anti-cancer drug inducing method and treated with 5-Aza-2′-deoxycytidine (5-Aza-CdR) for different periods of time. Runx3-shRNA expression vectors were transfected into drug-resistant HepG2 cells. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect Runx3 mRNA expression before and after transfection. C

ell viability was evaluated by MTT assay

and apoptosis was analyzed using Hoechst 33258. Flow cytometry (FCM) was used to detect the cell cycle distribution

and Western blotting was used to measure the expression levels of P-gp and Runx3.       Results       The expression of Runx3 mRNA was decreased with the increasing drug resistance against HepG2 cells. However

it was increased gradually after treated with 5-Aza-CdR

and cell proliferation was inhibited obviously. The cells at S phase and apoptotic cells were increased. Also

5-Aza-CdR resulted in a decrease of P-gp. Down-regulation of Runx3 in drug-resistant HepG2 cells promoted the cell proliferation

the cell cycle arrested at G

1

and increased expression of P-gp

which indicated that it inhibited the drug sensitivity.       Conclusion       Runx3 may play an inhibitive role in drug resistance

and up-regulation of Runx3 might prove cancer cells more sensitive to chemotherapy.